System and method for expandable non-volatile storage devices

ABSTRACT

A method and system is introduced to allow expanding the storage capacity of a storage device using other storage device units in a dynamic manner. The expanded device may emulate a single large capacity media device. Files existing on device prior to device expansion may remain valid following device expansion. Capacity of storage devices and digital appliances making use of storage devices may be expanded. Instead of replacing a device with a larger capacity device, storage capacity can be expanded. The device may allow implementing file access policies to protected files.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Ser. No.60/687,903, filed Jun. 7, 2005 by the present inventor.

This application uses the frammis vane disclosed in Provisional PatentSer. No. 60/658,568, filed Mar. 7th 2005 by the present inventor.

FIELD OF INVENTION

This invention generally relates to devices having non-volatile storage.

More particularly this invention relates to methods enabling theexpansion of non-volatile storage capacity.

BACKGROUND OF THE INVENTION

The use of non-volatile digital storage has been a rapidly growing withthe advancement of the computer market. The requirement for mobilenon-volatile storage has been growing with the use of computer laptops.Furthermore with the requirement for larger capacities for music playerssuch as the iPod player by apple (www.apple.com/ipod) the requirementfor digital storage is ever growing. Devices such as digital cameras andmobile phones are using non-volatile memory cards such as theflash-cards by Sandisk (www.sandisk.com) to store images and other data.Other devices of the Key-Chain Storage family by M-systems(www.m-sys.com) include USB connectivity for computers to act as afloppy disk replacement.

A unit of digital storage such as a computer hard disk, a flash card ora Key-Chain storage device and other such digital storage devices willbe referred herein as a digital media storage device, or a media device.

A media device, unlike a floppy diskette includes a controller with someRAM, and or ROM or other memory. This has become necessary as thesedevices became more complex, managing their media transparently to theappliance, for example, in order to hide media defects and manage themedia on a higher level.

A media device includes a certain constant amount of storage capacity,and is managed as a single unit by the appliance using it. For example,a computer hard disk is a single storage entity. If more storagecapacity is required, another hard-disk is added. This hard-disk is thenconsidered as a different volume and receives another drive letter inthe Windows operating system, or may be mounted within the directorytree of the existing hard-disk in a Unix operating system. In this case,a hard disk is a single unit of capacity meaning files cannot behomogeneously stored on both hard drives.

A media device such as a USB key-chain storage device has got a constantamount of storage similar to a hard disk. This capacity is constant. Itis formatted and it is then a single storage entity, which may beconnected to a Windows or a Unix system like the case in adding a harddisk.

The term digital appliance will be referring to appliances such as amultimedia player, a camera, a mobile phone, a PC and so forth. Thedigital appliance may include some internal unit of storage capacity,and may include an expansion slot for adding more storage capacity. Theadditional storage capacity available in the case of digital appliancesis similar to adding another volume in a computer. The storage availableis then viewed as two different storage volumes. This limits the user bynot being able to store a file larger than the maximum size of thedifferent volumes. Furthermore, the user has to be aware of thesedifferent volumes and manage them.

A user owning a media device with storage capacity X who would like toown a single media device with storage capacity X+Y, has to purchase anew media device with storage capacity X+Y. It is not possible to expandan existing media device of capacity X with another media device ofcapacity Y to form a single larger capacity media.

This limitation of not being able to expand media device capacity is dueto hardware and software reasons. On the hardware side, it is alwayseasier to design a single unit that does not require expansion. On thesoftware side, an operating system format such as FAT32, NTFS etc, is astatic format in the sense that the storage capacity of the media devicedoes not change. If the size of the capacity would somehow change,reformatting of the device is required to incorporate the new capacitysize, leading to the erasing of the entire media device contents.

A user owning a media device having a certain capacity cannot expand thecapacity of that device. Instead the user has to purchase a new mediadevice in order to get a larger media device. For digital appliancessuch as a multimedia players or any other appliance that includingnon-volatile storage, the case for capacity expansion is similar to themedia device problem. The device may have an expansion slot forincluding another storage volume, in which case an existing expansioncard has to be replaced. If there is no expansion slot available, theappliance has to be replaced to increase its capacity size.

Although for key-chain USB devices it is possible to carry several mediadevices and use them all, this is not practical since the need forlarger files is growing and having to split large files betweendifferent devices is cumbersome and not practical. Using several devicesis altogether not practical and cumbersome.

It is therefore a disadvantage that media devices as well as digitalappliances have to be replaced when increased capacity is desired. Thereis thus a widely recognized need for a media device that can bedynamically expanded to keep existing data valid through device capacityexpansion, and it would be highly advantegous to have such a devicedevoid of the above limitations/

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided amethod for dynamically changing data storage capacity of a data storagedevice the method comprising:

-   -   a. connecting an additional storage unit to said data storage        device;    -   b. expanding total storage capacity of said data storage device        using storage capacity of said connected storage unit;    -   c. storing files homogeneously on said data storage device and        any connected storage units.

According to a second aspect of the present invention there is provideda device capable of storing data files comprising:

-   -   a physical non volatile memory;    -   an extension connection for adding at least one storage unit to        said device, said device having an extension connection        interface to any connected storage units;    -   an internal processor;    -   an external file interface for accessing data files stored on        said device and any connected storage units;    -   whereby data storage commands received by said device through        said external file interface are translated by said internal        processor and information stored in said device non-volatile        memory to sectors of said device and sectors of any connected        storage units through said extension connection interface to        imitate a single data storage device.

According to a third aspect of the present invention there is provided afile storage device for storing files sectorially for subsequent access,the device comprising:

-   -   an external interface for accessing stored files on said device,        and an internal logic for virtualizing several storage units        into a single media device in a dynamic manner such that        connected storage units can be changed without requiring to        initialize the device.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The materials, methods, andexamples provided herein are illustrative only and not intended to belimiting.

Implementation of the method and system of the present inventioninvolves performing or completing certain selected tasks or stepsmanually, automatically, or a combination thereof. Moreover, accordingto actual instrumentation and equipment of preferred embodiments of themethod and system of the present invention, several selected steps couldbe implemented by hardware or by software on any operating system of anyfirmware or a combination thereof. For example, as hardware, selectedsteps of the invention could be implemented as a chip or a circuit. Assoftware, selected steps of the invention could be implemented as aplurality of software instructions being executed by a computer usingany suitable operating system. In any case, selected steps of the methodand system of the invention could be described as being performed by adata processor, such as a computing platform for executing a pluralityof instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features, and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanying drawings, in which:

FIG. 1A is a block diagram illustration of an expandable media devicewith N connected storage units connected to a digital appliance, inaccordance with an embodiment of the present invention;

FIG. 1B is a detailed block diagram illustration of an expandable mediadevice with N connected storage units connected to a digital appliance,in accordance with an embodiment of the present invention;

FIG. 2 is a schematic flowchart for reading and writing a sector of anexpandable media device, in accordance with an embodiment of the presentinvention;

FIG. 3 is a schematic flowchart for handling a change in storage unitsconnected to an expandable media device, in accordance with anembodiment of the present invention;

FIG. 4 is a block diagram illustration of a storage unit having adynamic enforcement policy and an independent user file table connectedto an expandable media device, in accordance with an embodiment of thepresent invention;

FIG. 5 is a schematic flowchart for dynamically securing a file on anexpandable media device, in accordance with an embodiment of the presentinvention;

It will be appreciated that, for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those of ordinary skill in the artthat the present invention may be practiced without these specificdetails. In other instances, well-known methods, procedures, andcomponents have not been described in detail so as not to obscure thepresent invention.

Several advantages of the present invention are to provide a way toexpand the capacity size of a media device; to provide a way to make useof several media devices that may be combined to form a single mediadevice with capacity of the total accumulative size of the mediadevices; to be able to expand the memory of digital appliances thatinclude media devices; to provide a way to expand the capacity of amedia device in a manner that may allow to keep existing data of mediadevice valid.

In the description herein below, the term “Non-Volatile Storage” refersto storage media that remains unchanged when power is shut off. Forexample, Flash memory and Hard Drive magnetic media.

In the description herein below, the term “Cluster” refers to a groupingof consecutive sectors of data in a Media Device.

In the description herein below, the term “Storage Unit” refers to asingle unit, which includes an amount of non-volatile memory. This unitmay be in itself a media device as well as a unit for capacity expansionpurposes, or this unit may only be added to another device for expansionpurposes.

In the description herein below, the term “Expandable Unit” refers to asingle unit, which one or more storage units may connect to, and mayconnect to a digital appliance.

Reference is now made to FIG. 1A, which is a block diagram illustrationof an expandable media device with N connected storage units connectedto a digital appliance, in accordance with an embodiment of the presentinvention comprising an expandable storage unit 10 having N connectedstorage units connected to a digital appliance 20. N storage units areconnected to expandable storage unit 10. The N storage units are shownin FIG. 1 from storage unit 112 to storage unit N 14. Storage units maybe added and removed from expandable storage unit 10. The expandablestorage device 10 seems as a single device to digital appliance 20,having a total capacity of the sum or nearly the sum of connected Nstorage units. Storage units may be added to expandable storage unitafter expandable storage device is formatted and being used so thatadditional storage space can be used. Storage units may be removed fromexpandable storage unit after expandable storage device is formatted andin use. In case of storage units removal some files may be removed. Thisis due to the fact that files may become broken such as miss a portionof data when a storage unit is removed. The possibility of changing thephysical size of a memory device is displayed in this invention. In someembodiments the presented possibility of changing the physical size of amemory device takes place while data already on device is preserved.Data preservation occurs when storage units are added, while for removedstorage units data preservation takes place for files unaffected by datastored on removed storage units.

Reference is now made to FIG. 1B, which is a detailed block diagramillustration of an expandable media device with N connected storageunits connected to a digital appliance, in accordance with an embodimentof the present invention comprising an expandable storage unit 100having N connected storage units connected to a digital appliance 120. Nstorage units, from storage unit 1 130 through storage unit N 140, areattached to expandable storage unit 100. This FIG. is similar to FIG. 1Awith a detailed expandable storage unit 100. The expandable storage unit100 includes non-volatile storage 104, an internal processing module 102capable of data processing such as a CPU, an I/O module 114 capable ofcommunicating with digital appliance 120 and a storage unit interface116 capable of communicating with connected N storage units. Thenon-volatile storage 104 contains sector table 106 and allocation table108. N storage units from units 1 130 to unit N 140 are attached toexpandable storage unit 100. The storage units interface with theexpandable unit 100 through the storage unit interface 116. The storageunit number may vary from 1 to any number N. The non-volatile storage104 may contain other information such as conversion tables andallocation table mirrors for each storage unit. In some embodimentsstorage units may connect to expandable unit and be connected to oneanother in a serial manner.

The expandable unit 100 in this embodiment does not have any user datastorage but in some embodiments may include a storage unit. Theexpandable unit 100 includes an allocation table 108 for the entirestorage capacity of the expandable media device. For example, in a FAT32file system the allocation table 108 contains the entire file allocationtable for the expandable media device. The sector table 106 includes atable that holds location information for each sector within theexpandable media device. This table may include redirection of sectorindexes into allocation table 108 and N storage units. The table mayassist to translate a requested sector number by digital appliance 120received through I/O module 114 to a sector within a storage unit orallocation table. The translation table of sector table 106 may includea sector number offset for each storage unit, as well as corrections,for example, in case the number of sectors per cluster may not beuniform upon all storage units.

During operation, the digital appliance 120 views the expandable mediadevice as a single media device having an allocation table. Theallocation table resides within allocation table 108. When fileoperations occur by digital appliance 120, allocation table updates areconverted into updates within allocation table 108. Data sector read andwrite operations are converted through sector table 106 to the requestedsector within a storage unit in a manner that corresponds to the sectorrequested. It is the sector table 106 responsibility to make thecorrespondence between requested sector by digital appliance 120 andsector within storage unit or allocation table.

When another storage unit, N+1, is attached to an expandable mediadevice having N storage units connected, the expandable media devicedetects the change through expandable unit interface 116. As a resultnecessary changes are made to sector table 106 and allocation table 108in order to dynamically form a single virtual device with total storagecapacity of expandable media device having N storage units with theadditional storage capacity of storage unit N+1. The files on expandablemedia device with N storage units may remain valid following theaddition of storage unit N+1. This process is illustrated in FIG. 3.

Internal processing module 102 may have access to various types ofvolatile and non-volatile memory such as RAM, ROM, FLASH, EPROM,Magnetic Disk media etc, not included in the drawing for clarity. Pleasenote that other modules may be included in the expandable media devicenot included in the drawing for clarity.

In some embodiments each storage unit includes other modules such as aCPU as well as others.

In some embodiments the expandable device may not be separate from adigital appliance as illustrated in FIG. 1A and 1B, but may be a singleunit containing non-volatile memory, such as mobile multimedia players.In some cases the number of storage units attached to expandable mediadevice may range from 0 to a constant M.

In some embodiments each storage unit may include an allocation table,which may be kept updated by expandable storage unit 100, for exampleaccording to sector table 106 and allocation table 108. In someembodiments sector table 106 and allocation table 108 may be deducedupon initialization of expandable media device from the allocation,tableof each storage unit. In some embodiments having this deduction mayallow an embodiment without using non-volatile memory for sector table106 and allocation table 108. In some embodiments where each storageunit allocation table is kept updated separately, each storage unit maybe added or removed from expandable media device. In this case a storageunit may be used separately or in a different form of collection ofstorage units, either on its own or with other storage units. In thiscase a single large file may be divided into separate files in eachstorage unit.

In some embodiments where some file access may be protected from digitalappliance, such as in reference to patent application “System and MethodFor A Dynamic Policies Enforced File System For A Data Storage Device”filed Mar. 7th 2005 by the present inventor, protecting of file contentsmay be accomplished in accordance with sector table 106 and allocationtable 108. In some embodiments file content protection occurs separatelyin each storage unit. A method for protecting a file that is splitbetween several storage units is presented in FIGS. 4 and 5.

In some embodiments each device may also function as a storage unit. Insome embodiments each device includes a connection for expansion suchthat devices may be stacked to expand storage capacity.

Reference is now made to FIG. 2, which is a schematic flowchart forreading and writing a sector of an expandable media device, inaccordance with an embodiment of the present invention.

In step 201 digital appliance requests sector K of expandable mediadevice to be read or written.

In step 202 sector K of expandable media device is translated to sectorK′ at storage unit N′. This translation is carried out by sector table106 and processing unit 102. The sector table holds informationregarding a correspondence between virtual sectors of virtual singleexpandable media device and real sectors in a storage unit or allocationtable space. When a sector K is requested, the sector table informationis viewed to find the actual location where the virtual sector Kresides. The information in sector table 106 returns which storage unitor allocation table storage area the requested sector is located N′ aswell as the number of sector within that unit, K′. This translation mayhide the sector segmentation of storage unit 1 130 to storage unit N140, as well as the allocation table size, and other adjustments such asdifferent number of clustering which may exist between the storageunits. This translation hides the different sets of sectors into asingle consecutive media device having a single allocation table, asingle continuous data storage area with a constant number of sectorsper cluster.

Different number of sectors per cluster may be implemented. For example,the expandable media device unit may be configured to have 1 sector percluster while the actual sectors per cluster may actually be 8 in thestorage unit K′. Upon a sector request the expandable unit may read theentire cluster from the relevant storage unit and return the requestedsector out of the cluster.

Sector table 106 may allow keeping track of physical sectors in storageunits, converting them to virtual sectors in accordance with allocationtable 108.

In some embodiments continuous sectors in virtual expandable mediadevice correspond to continuous sectors in each storage unit andallocation table space, allowing for better performance with minimumrange checking.

In step 203 sector K′ in storage unit N′ is read or written asrequested, completing the requested operation as if sector K of a singledevice has been read or written.

This series of steps displays how read sector and write sectoroperations may be carried out with the expandable media device in amanner that makes several different storage units appear as a singlestorage unit to digital appliance.

Reference is now made to FIG. 3, which is a schematic flowchart forhandling a change in storage units connected to an expandable mediadevice, in accordance with an embodiment of the present invention.

In step 301 a consistency check is made at start of usage, such as whenan expandable media device is connected to a digital appliance. Thischeck is made in order to identify if storage units previously connectedare still in place and if storage units have been added or removed sincelast device usage. This check may be made with the assistance of storageunit interface 116, allocation table 108, sector table 106, and storageunits 130 to 140.

In step 302 consistency check of step 301 may be analyzed, whether achange to storage units has been made. If no change has been made, step303 follows. If a change has been detected, step 304 follows.

In step 303 the device continues to normal operation, such asillustrated in FIG. 2. This is possible since no change has been madeand the expandable device is consistent.

In step 304 sector table 106 is adjusted according to new storage units.This adjustment may change the size of the allocation table 106 so thata smaller or larger number of sectors will be used for allocation table.Existing storage unit sector number mapping may be changed to facilitatethe current size of the expandable media device. Additional storage unitsector numbers may be added for the sector table mapping to facilitate alarger size expandable media device. In some embodiments cluster numbersare used instead of sector numbers. In some embodiments a mixture ofsector numbers and cluster numbers are used.

In step 305 portion of allocation table is optionally backed up. Thismay be done for example in a case where a storage unit is removed andsome of allocation table 108 is removed. In order to allow restoring theexpandable media device at a later time by returning the removed storageunit, some of the information of the allocation table 108 may be backedto non-volatile memory 104.

In step 306 adjustments are made to allocation table 108 according tosector table 106. For example, if storage units are added thenadditional storage is prepared and initialized to serve as part of theallocation table.

In step 307 the device continues to normal operation as a single mediadevice.

In the following paragraph an exemplary embodiment of an expandablemedia device using a FAT32 file system is used to describe processesoccurring when adding an additional storage unit to an expandable mediadevice while preserving existing data files on expandable media device.In FAT32, files and directories are contained in clusters numbered from2 onwards. The cluster numbering starts following the FAT32 allocationtable herein referred to as FAT. Since the FAT may be held withinexpandable unit 100 at allocation table 108, more storage for FAT may beavailable within allocation table 108 than is currently in use. FAT maybe enlarged to reflect the added storage of the additional storage unit,by adding entries to the FAT according to the added number of clustersin the added storage unit. Following the FAT expansion, sector table 106is updated to route added allocation table sectors to allocation table108 and to route cluster 2 and onwards to sector numbers incremented bythe addition of sectors used in allocation table 108. Sector table 106is then updated to route added capacity clusters to the added storageunit. In addition, some necessary value changes to FAT data withinallocation table 108 of expandable unit 100 may be made to imitate alarger capacity media device, such as total number of sectors inpartition, number of sectors per FAT, number of free clusters, etc.These are values located at the start of any standard FAT such as MasterBoot Record and Volume ID sector. In some embodiments the added storageunit may be formatted with FAT32 format. In this case the expandableunit 100 may use the storage unit clusters while the FAT of the storageunit may remain unused. In some embodiments the FAT of the storage unitmay be kept updated by expandable unit 100. As explained above, clusternumbering previous to capacity expansion remain unchanged followingcapacity expansion. Therefore existing files on expandable media deviceprior to capacity expansion may remain valid following capacityexpansion. Note that in FAT32 two copies of FAT exist. When FAT size isincreased both copies sizes increase.

Preserving existing files upon the removal of storage units from anexpandable media device is problematic because data belonging to datafiles may be present on removed storage unit. In case of storage unitremoval it may be possible to preserve files that none of their dataportions exist on the removed storage device. It may be possible to useexternal software to allow moving data between storage units in order toallow emptying a storage unit for removal.

When a storage unit is removed, similar steps may be taken to the abovecase of adding storage units in order to preserve existing data fileswith no data portions on the removed storage units. The steps that maybe taken are decreasing allocation table 108 size to accommodate asmaller-sized device. Sector table 106 changes absolute sector mappingso that a smaller number of sectors are used in the allocation table.Sector table 106 changes mapping to decrease removed storage unitclusters. In addition, changes to FAT may be required due to changes incluster numbers that may be in effect if a storage unit is removed.Other changes to FAT may be required as indicated above.

Following the removal of a storage unit an application or an internalprogram may be carried out on the expandable media device, so that filesthat now may miss some or all of their data clusters may be handled. Oneapproach for such handling may be to remove partial files. Otherapproaches may be to store remaining file parts on media device ortransfer partial files to digital appliance 120.

In some embodiments the handling process for changing storage unitsoccurs at time of connection of expandable media device to digitalappliance 120.

In some embodiments the process of adding and removing storage units mayoccur at different or additional times to device connection to digitalappliance. In some embodiments this process occurs at device power up.

In some embodiments it is not required to format the expandable mediadevice when adding a storage unit. This is possible similar to themanner as explained when existing files are kept following the additionof a storage unit. The FAT area is increased within allocation table108, sector table redirects data as required according to FAT new sizeand added storage size of additional storage unit. Some values arechanged in the file system header to reflect additional change in sizeas indicated above in the case for allowing existing files to remain.Additional FAT sectors within allocation table may require to beinitialized such as being set to zero. In a similar manner it is notrequired to format the expandable media device when removing a storageunit.

This series of steps displays how expandable media device may handlechange in storage units in order to expand or decrease storage size. Thechange of storage units may allow to keep files on expandable mediadevice that exist prior to change in connected storage units.

In some embodiments data files may be protected from digital appliance,such as in reference to provisional patent application “System andMethod For A Dynamic Policies Enforced File System For A Data StorageDevice” filed Mar. 7th 2005 by the present inventor. In such embodimentsthe protection of files may be accomplished for a single storage unit. Amethod to protect a file that is split between several storage units maybe accomplished as described in FIGS. 4 and 5 as follows.

In the description herein below, the term Logical Block Addressing or“LBA” refers to a method for addressing sectors where instead ofreferring to a drive's cylinder, head and sector number geometry, eachsector is assigned a unique sequence number. In essence, LBA is a meansby which a drive is accessed by linearly addressing sector addresses.The LBA method is being used for general media devices and will be usedherein to define a virtual media address of a media device.

In the description herein below, the term “Physical User Media” refersto non-volatile storage of storage unit available initially to the user.

In the description herein below, the term “Internal User File SystemAnalyzer” refers to a method of accessing user file information by mediadevice.

In the description herein below, the term “Internal File Table” refersto a file table information store kept within storage unit not availableto digital appliance. This information may be a copy of some or all ofuser file table information.

In the description herein below, the term “Dynamic Security PolicyEnforcer” refers to a method of protecting access to non-volatilestorage LBAs, according to each LBA policy.

In the description herein below, the term “LBA DB” refers to a databaseallowing marking LBAs of storage unit with access policy types.

In the description herein below, the term “Decryptor/Validation” refersto unit which may decrypt or validate data, internally to storage unit.This method may be accomplished by using an internal key availableinternally to storage unit.

Reference is now made to FIG. 4, which is a block diagram illustrationof a storage unit having a dynamic enforcement policy and an independentuser file table connected to an expandable media device, in accordancewith an embodiment of the present invention comprising a storage unit400 connected to an expandable media device 422. The storage unit 400includes physical user media 402 where user non-volatile data is stored,a dynamic security policy enforcer 404 for enforcing policy rules foraccessing physical user media, which will be referred to herein aspolicy enforcer. The storage unit further comprises internal independentuser file system table and processing unit 412, and an I/O module 420for communication. The policy enforcer 404 supports two different setsof API calls in this embodiment, API 1 408 and API 2 410. The policyenforcer 404 includes an LBA database 406, where rules regarding accessto sectors within physical user media 402 are kept. The internalindependent user file system table and processing unit 412 comprises aninternal processing module 418 for internal computing, internal userfile system analyzer 414 for analyzing user file system in physical usermedia 402 independently, an internal file table 416 for storing filetable information from analyzer 414, a decryption/validation module 419and Keys 417. The user physical media 402 refers to the media that maybe accessed and used by the expandable media device 422. This media maybe accessed through LBA numbering. The policy enforcer 404 may manageaccess to the user physical media 402 in a manner, which depends uponthe LBA that is being accessed, the operation requested and the API thatis being used for access. The LBA database 406 may include policyentries for LBAs in the physical user media 402. For example, the LBAdatabase may include a policy entry for each of the LBAs in the physicaluser media 402, specifying the policy for each LBA such as which of theLBAs are accessible from outside the storage unit. In another example,only policy entries that are different to a default policy are kept. Thedynamic property of the policy enforcer 404 is accomplished by allowingdynamic changes within the LBA database for each LBA in the physicaluser media 402, pending an appropriate API request. The fact that thepolicy enforcer 404 is internal to the storage unit 400 and inaccessibleby the expandable media device 422 is a preventive measure againstinappropriate access. In this implementation, two different policies areused. In other implementations more types may be used. The invention isnot so limited. The internal independent user file system table 412 maycontain information about the files parts contained in the physical usermedia, such as the order and location of sectors or clusters making up afile. In case the storage unit file allocation table is active andrelevant, this information may be gathered by the internal user filesystem analyzer 414, which mounts the user's file table and extract userfile information. In case file table of expandable media device is used,information may be accessed through I/O module 420 from expandable mediadevice 422. This information may then be copied to internal file table416. Other manners of accessing user file table exist, such as bydigital appliance 120 connected to expandable media device. In someembodiments the digital appliance 120 may extract user file tableinformation and pass the information to the expandable media device inparts, which may be kept in volatile memory and/or in non-volatilememory. The internal independent user file system table 412 has accessto each LBA of the physical user media 402 through non-limiting API 2while the expandable media device and digital appliance 120 have accessto each LBA of the physical user media 402 through limiting API 1. Inthis manner an internal processing unit 418 is able to access file dataexisting within the physical user media 402 independently, and navigatethrough user files with the help of the internal file table 416. Thisindependent access allows internal processing unit 418 to makecomputations based on data, which is not accessible to expandable mediadevice and to digital appliance and output the results through I/Omodule 420 or to physical user media 420. In this manner data isprotected as required by rules in dynamic security policy enforcer 404.

Please note that to the internal processing module 418 may be accessiblevarious types of volatile and non-volatile memory such as RAM, ROM,FLASH, EPROM, Magnetic Disk media etc, not included in the drawing forclarity.

With the addition of a decryptor/validation module 419 and keys 417, afile or a portion of a file may be transferred securely to the mediadevice for use only through internal processing. FIG. 5 presents amanner in which a secure file is transferred securely into media devicestorage units.

In some embodiments the internal media table 416 may exist on thephysical user media 402.

The internal processing unit 418 may use internal file table and otherinternal data in conjunction with data of physical user media 402available through API 2 in order to process and output data. Theprocessed output data may be placed into a file in the physical usermedia 402 readable through API 1 408 using the internal file table 416,for digital appliance 120 use. Other manners of passing processed datato the digital appliance 120 may be made, such as through I/O module420.

In some embodiments expandable storage unit includes a dynamic securitypolicy enforcer and an internal independent user file table.

Reference is now made to FIG. 5, which is a schematic flowchart fordynamically securing a file on an expandable media device, in accordancewith an embodiment of the present invention.

In FIG. 5 an encrypted file is delivered to expandable media device.Expandable media device then makes the file inaccessible to digitalappliance and decrypts the file internally for internal use.

In this embodiment a secure file is encrypted with a key and eachstorage unit has the key to open the secure file. This scenario may beimplemented by sending the key to each storage unit in a secure manner.

In step 501 the secure encrypted file is placed in the physical usermedia of the expandable media device, for example by copying the fileonto the expandable media device or transferring it from the Internetonto the expandable media device. The file may be physically storedwithin several storage units, each including some portions of the file.

In step 502 the expandable digital media cache and buffers are beingflushed. This is done for example in Linux by the utility Sync. InWindows this is done for example by a utility Sync fromwww.sysinternals.com.

In step 503 the file system of the user is mounted from within theexpandable media device within each storage unit. This mounting mayinclude the recent file now that the digital appliance has flushed itsbuffers. File table may exist in expandable unit 100 or within storageunits or both, depending on implementation.

In step 504 the LBA indexes making up the file parts within each storageunit are collected from the file system table. This may be done usingthe expandable media device single file system table, which may bestored in allocation table 108, or from storage units file system tableif applicable. For example in a FAT32 file system of the expandablemedia device, the first cluster is included in the file's directoryentry. The next cluster entry is included in the FAT entry for the firstcluster. The next cluster is included in the FAT entry of the previouscluster and so forth. The LBA order of indexes is translated from thecluster numbers above to the actual clusters within each storage unitthrough sector table 106. In some embodiments digital appliance maytransfer LBA addresses to expandable media Device. In some embodimentsexpandable unit 100 transfers LBA addresses to each storage unit.

In step 505 an internal file entry including file part name and LBA listwithin that storage unit is created in the internal file table 416 ofeach storage unit including a file portion of file to be protected. TheLBA list may contain more than a single file part. The file entry iscreated in a location unreachable to the digital appliance. Theinformation stored may include the file name, the LBA list and order ofwhere the file data on the physical user media 402 is kept. The filestatus in the internal file table 316 is marked as “pending” and cannotbe used at this time.

In step 506 LBA numbers for each file part in each storage unit is addedto LBA database of storage unit, making these LBA numbers belonging toencrypted file readable only internally to storage unit. These LBAnumbers become unreadable through API 1 408 and readable through API 2410.

In step 507 consistency check and/or decryption is run in sequence forthe current file part where it resides in storage unit S. The first filepart of the file is used when step 507 occurs for the first time.

In step 508 we check if the file part just executed in step 507 is thelast file part of the file so that the file is complete. If yes, step509 follows. If no then there is another file part and step 520 follows.

In step 520 next file part is identified as the next set of sequentialportion of sectors in a storage unit S′. Current processing data such asconsistency and decryption variables are passed from storage unit S tostorage unit S′ in order to allow to continue validation and/ordecryption.S′ then turns into S and step 507 follows for validatingand/or decrypting this next file part.

In step 509 A check is made to see if the file is consistant throughchecking validation information of the file. Verification process mayinclude a digital signature such as SHA1. If file is consistent step 510follows. If file is inconsistent step 530 follows.

In step 530 go to erase hidden file parts. This step occurs when file isdetermined to be inconsistent and the file parts are erased by firstwiping all LBA data belonging to file in each file part, then removingfile entries in user file table and lastly removing LBA numbers of filefrom LBA database. In some embodiments the erasing process may not occurat this time.

In step 510 inner file is marked with status “usable”. This is becausethe file is consistent and can be usable safely within expandable mediadevice. File can now be used through API 2 410.

In step 511 attributes of user file or attributes of entire file areoptionally changed within the user accessible file table. This may beperformed so that the user may not attempt to use or modify the securefile. File attributes may be changes to “System”, “Hidden”, Read-Only”and so forth so that the file may not be accidentally removed by theuser and that a de-fragmentation operation may not attempt to change thephysical location of this file. Marking file sectors (or clusters) as“bad” so that the digital appliance may not use the sectors is also apossibility.

Usage of protected file may be accomplished within each storage unit, byusing API 2 410 from within storage unit to access protected file part.In addition, other information may be communicated between storage unitsin various manners. Processed information may be made available todigital appliance through API 1 408 or other means.

This series of steps displays how a file may change its security policydynamically within an expandable media device. A file may be verifiedand decrypted while kept inaccessible to digital appliance throughoutverification and decryption process occurring within each storage unitcontaining one or more file part of file being secured. Consequentlyverified and decrypted file may be used within storage units accordingto specified security rules for the secured file.

This dynamic property of file policy is made possible through the LBAdatabase 406 and the internal file table 416. The internal file table416 gathers independent meta-data file information for the dynamicsecurity policy enforcer 404. This information allows changing LBApermission to the correct LBA indexes making up the file through the useof the LBA database 406. Even if a user attempts to change the fileallocation table of the expandable media device or storage unit filesystem header, the file will remain secured due to the fact that thefile meta-data is managed through the internal file table 416. The LBAdatabase protects the correct LBA indexes as listed in the internal filetable 416. The data may be safely used once file is internally verified,such as with a digital signature.

Processing of file portions within each storage unit may be accomplishedby passing data between storage units when processing is made betweenfile portions within different storage units.

It may be appreciated by those skilled in the art of the presentinvention that the following advantages exist in this invention, overthe existing mechanisms:

-   -   (a) With the present invention, it may be possible to expand the        storage capacity of a media device by adding other storage units        to the media device.    -   (b) The present invention may allow expanding the storage        capacity of a media device with other storage units by emulating        a single device with an expanded storage capacity. This may        allow storing large data files of size up to the new expanded        storage capacity, as well as adding additional files to the same        device volume.    -   (c) The present invention may allow expanding the storage        capacity of a media device while keeping the existing user data        on the media device.    -   (d) Media device allows placing files with different access        policies on expanded storage space.    -   (e) The present invention allows using files with access policy        protection on expanded storage devices.    -   (f) The present invention may allow expanding the storage        capacity of a media device while keeping the existing protected        data on the media device.

Conclusion, Ramifications and Scope

Accordingly, the reader will see that the closure of this inventionprovides a method to expand the storage capacity of a media device withother media device storage units. The expanded device may emulate asingle large capacity media device of the size of the accumulatedcapacity of the storage units. The ability to expand media devicecapacity allows continuing using a single media device rather thanreplacing device due to insufficient size.

Furthermore with the expandable media device, there are additionaladvantages in that:

(a) Adding more storage to an existing expandable media device may allowkeeping user data files valid while increasing total device volumecapacity.

(b) Large files may be stored on the expandable media device. The sizeof a file may exceed any single media device unit capacity used by theexpandable media device.

(c) More files may be stored on expandable media device in the samedevice volume, following device expansion.

(d) The capacity of digital appliances that make use of a media devicemay be expanded. This may allow continuing using a digital appliance byexpanding its capacity rather than by replacing it.

(e) The expandable media device may support standard operating systemfile formats not requiring a special or proprietary file system.

(g) The expandable media device may allow using files with a protectedpolicy in addition to user files on the same volume.

(h) Adding more storage to an existing expandable media device may allowkeeping data files with a protected policy valid while increasing totaldevice volume capacity, for protected and unprotected file usage.

Although the description above contains many specifications, theseshould not be constructed as limiting the scope of the invention but asmerely providing illustrations of some exemplary embodiments of thisinvention.

For example, the expandable unit 100 may include user data space.Storage units may be added in serial to expandable unit 100, or in otherways. Each storage unit may be similar to an expandable unit 100. Eachstorage unit may be used independently on its own. Each storage unit maybe different to the expandable unit 100. The specified names, expandableunit and storage unit have been made for clarification purposes and notto be limiting; Any type of operating system format may be used otherthan FAT32, such as NTFS, UNIX file system etc; The expandable unit maybe a part of a digital appliance. This may be used to expand storagecapacity for a digital appliance. Digital appliance may be any devicethat makes use of digital storage; Allocation table 108 and sector table106 are helpful for explanation purposes. Some embodiments may notinclude these as they may be deduced from storage units that are up todate; Storage units may be made to be used on their own or inconjunction with other storage units; Files which are split betweenstorage units may be named as a file parts on storage units; Files maybe protected from digital appliance in other manners than described;Adding or removing of storage units from expandable media device mayoccur at a different time to power up of device; In order to preservefiles following storage unit changes, rewrites to file allocation tablemay be necessary to make adjustments.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

What is claimed is:
 1. A method for dynamically changing data storagecapacity of a data storage device the method comprising: a. connectingan additional storage unit to said data storage device, b. expandingtotal storage capacity of said data storage device using storagecapacity of said connected storage unit, c. storing files homogeneouslyon said data storage device and any connected storage units.
 2. A methodaccording to claim 1 wherein said data storage device and any connectedstorage units prior to said storage capacity expansion do not requireformatting following said storage capacity expansion.
 3. A methodaccording to claim 1 wherein existing data files on said data storagedevice and any connected storage units prior to said storage capacityexpansion are kept following said storage capacity expansion.
 4. Amethod according to claim 1 wherein removal of one or more storage unitsfrom said data storage device decreases total size of said data storagedevice.
 5. A method according to claim 4 wherein no formatting of saiddata storage device is required following said data storage removal. 6.A method according to claim 4 wherein existing data files on said datastorage device prior to said data storage units removal are keptfollowing said removal of data storage units for files not broken bysaid removal of storage units.
 7. A method according to claim 3, whereinsome of said data files have restricted access conditions therebyallowing full access to unrestricted files and restricting access torestricted files.
 8. A device capable of storing data files comprising:a physical non volatile memory; an extension connection for adding atleast one storage unit to said device, said device having an extensionconnection interface to any connected storage units; an internalprocessor; an external file interface for accessing data files stored onsaid device and any connected storage units; whereby data storagecommands received by said device through said external file interfaceare translated by said internal processor and information stored in saiddevice non-volatile memory to sectors of said device and sectors of anyconnected storage units through said extension connection interface toimitate a single data storage device.
 9. The device of claim 8, whereinno formatting to said device and any connected storage units is requiredwhen adding at least one storage unit to said device through saidextension connection.
 10. The device of claim 8 wherein existing fileson said device and any connected storage units are kept when adding atleast one storage unit to said device through said extension connection.11. The device of claim 8, wherein no formatting to said device and anyconnected storage units is required when removing at least one storageunit from said device through said extension connection.
 12. The deviceof claim 8 wherein existing files on said device and any connectedstorage units are kept when removing at least one storage unit from saiddevice through said extension connection for files not broken by saidstorage units removal.
 13. The device of claim 8, wherein said devicefurther comprises an internal inaccessible interface located abovesector level access to limit access to certain data files according toan indication associated with a respective file of a file accessrestriction.
 14. The device of claim 8, wherein said storage unitsfurther comprises an internal inaccessible interface located abovesector level access to limit access to certain data files according toan indication associated with a respective file of a file accessrestriction.
 15. The device according to claim 10, wherein a sectortable is stored in said physical non-volatile memory of said device tomap at least part of external sectors to external storage units.
 16. Thedevice according to claim 15, wherein file system allocation table isstored in said physical non-volatile memory and kept separate from userstorage area thereby allowing said file system allocation table toexpand dynamically when said device size is increased.
 17. The device ofclaim 10, wherein each of connected storage units independently managesfile system and allocation system and said device manages virtualizingsaid device as a single storage device.
 18. A file storage device forstoring files sectorially for subsequent access, the device comprising:an external interface for accessing stored files on said device, and aninternal logic for virtualizing several storage units into a singlemedia device in a dynamic manner such that connected storage units canbe changed without requiring to initialize the device.
 19. The filestorage device of claim 18, wherein existing files on said device andany connected storage units are kept when adding at least one storageunit to said device.
 20. The device of claim 18 wherein existing fileson said device and any connected storage units are kept when removing atleast one storage unit from said device for files not broken by saidstorage units removal.